It worked!!! Didn't have time to program the motors or hang the screen, but it worked. I'm so frigging happy
I'll take some video of the mechanism when the screen is on the wall. That is if it still works when vertical
Just in case this inspires anyone else to build one here are the final details.
I added up all the receipts, total cost was $2123. A little over my original estimate but still about 1/8 of the cost of a commercial system.
Here is some detail on the leading edge of the masks. The picture show how the bungee cord was attached to the slider with two grub screws. Note that the lower hole was elongated to prevent binding if the horizontal frame wasn't perfectly parallel. I also drilled a couple of holes in the flat section so I could sew the fabric tight and flat.
The masks were made from GOM FR701 with a 2 1/2" pocket on the leading edge sewed from felido velvet. The holes in the aluminum allowed me to keep the fabric tight at the ends. This isn't a very good picture but it shows the no stretch edging strip made from iron on hemming tape (single sided) on the back side of the panel. This has the added advantage of stopping the GOM from fraying.
Once assembled the masked were fed in from the ends as I tightened the bungee at the opposite end (the bungee simply exits through a hole and is tied off with a knot). I made room for up to 3/16" bungee but in the end the 1/8" stuff seems to provide adequate pull. If it starts to sag over time I'll upgrade it.
Once the fabric was squared up and stuck to the roller with double sided tape the two side pieces were installed.
Hopefully my RS50 will arrive soon so I can show some screen shots... what do you to reckon Jason?